J. liendericks & P Ziveri.· Orastmm colligatum, a new species .. .. , p. 109-111.

Joumal of Nannoplankton Research, 19, 2, 1997.

ORASTRUM COLLIGATUM, A NEW HOLOCOCCOLITH SPECIESFROM THE CENOMANIAN OF THE RUSSIAN CRATON (UKRAINE).forijntje Henderiks, Geologisches !nstitut, ETH-Zentrum, CH-8092 Ziirich , Switzerland &Patrizia Ziveri, Geomarine Center, Vrije Universiteit, De Boelelaan 1085, 1081 !-IV Amsterdam, 771e Ne therlands

Abstract: A new ho lococcolith species, Orastntm colligatum sp. nov. , is described from well-preservedassemb lages from the Cenomanian deposits in proximity to Bryansk, Ukraine. The holococco lith ischaracteri sed by four smoo th , interlocking, crystallographically-coherent blocks . Similarities to , anddi stinct mo rphologica l ditTerence s from. other holo coccolith taxa are di scussed .

Introduction·During the course of an investigation of Upper AlbianTuronian calcareous nannofossils from the Russian Craton(Henderiks, 1996), a new holococcolith species was encountered in Nannofossil Zones CC9-1 0 (the Eiffellithus
turriseiffelii and Microrhabdulus decoratus Zones ofSissingh, 1977, later refined by Perch-Nielsen, 1985)
Both the relative abundance (up to 14%) and the restrictedvertical occurrence of this species in the studied sections
have made it suitable for biostratigraphical correlation inthis region . This new species is described herein. The
material was collected by Dr. A. V Ilyin (Institute ofLithosphere. Moscow, Russia) . Location details are provided in Ilyin (1994. fig.3. sections I and V) .
Taxonomy
The type-material and photographic negatives are deposited in t11e National Natural History Museum, Leiden, TheNetherlands. All taxa and taxonomic references appearing herein can be found in BO\vn (in press).
Genus: ORASTRUMWind & Wise in Wise & Wind,
1977
Type SJlecies: Orastrum asarotum Wind & Wise in
Wise & Wind, 1977
Ora~trum colligatum Henderiks & Ziveri SJl. nov.

Plate 1, Figures 1-7
Diagnosis : Medium-sized, elliptical, moderatelybirefringent holococcolith constructed of four smooth.
interlocking. crystallographically-coherent blocks, form ing an offset X in the central area.
DescriJltion: The new holococcolith consists of fourblocks, each possessing a bar which extends into the central area. These bars interlink in an offset X and bear lateral teeth w·hich project into the elongated central-area
perforations and are visible with the SEM in both distaland proximal views.
A distal SEM view (Plate I, Figs 1-2) reveals deeply
1
incised sutures separating the four blocks. The sutures arepartly obscured by the rectangular sides of the two blocks
that lie about the short ellipse axis, which overlap theother two blocks. The sutures in the central X-structure
are straight , although partly obscured by calcite
overgrow! h.
In proximal SEM view (Plate 1, Figs 3-4), tlle overall smoothness of the blocks is very clear and the sutures
between them are slightly curved and deeply incised. The
characteristic interlocking pattern of the blocks is clearly
displayed under cross-polarised light (Plate 1, Figs 5 and 7).

Dimensions: Holotype - length ..:t. . 8~m. width 3.3~m.
Paratypes - maximum length 6.4~m . maximum width
4.211111.
Remarks: This species is placed in the holococcolith genus Orastrum because the distal surface of theholococcolith does not support a ridged stem, as described
for the holococcolith genera Calculites andLucianorhabdus (see Farhan et al. ( 1994) for discussion).
0. colligatum also appears not to possess microcrystalline
structure and to be non-cavate, being composed of four
blocks with crystallographic continuity, as attributed toOrastrum (Farhan et al. , 1994 ). The new species does notpossess a central pore, unlike Calculites, Lucianorhabdus
and 0. asarotum , nor an elongated slit down the centre of
the coccolith, as in Orastrum porosuturalis, but instead
possesses a central X which encloses four
equidimensional, elongated perforations, into which teeth
extend laterally.
The similar stratigraphical ranges of the newlydescribed holococcolith and Calculites anfractus makes
a detailed comparison necessary. As opposed to the original description of Jakubowski ( 1986), 0. colligatum does
not display an occluded central structure characterisedby an S-shaped suture, but instead the previously
described central X-structure. More extensive calcite
overgrowth might result in an occluded central structure
in 0. colligatum , with the zigzag sutures as described forC. anfractus, but in this study no distinctive preservationalvariability was observed with the LM, both within thesame sample and throughout the Gm interval in which thespecies was encountered. Therefore, we describe a newspecies, but acknowledge that it is morphologicallysimilar to C. anfractus.
Derivation of name: Latin colligatum , meaning 'bound,tied together', referring to the interlocking blocks which
comprise this species.
Occurrence: 0. co lligatum is present in Nannofossil
Zones CC9 and possibly CC I 0 (uppermost Albian-Middlc Cenomanian) in two sections located near Kiev (Kurskand Bryansk region) , Ukraine. Throughout the interval
containing 0. colligatum (samples 94K4/6-13), thenannofloral assemblages contained Eiffellithus
turriseiffelii and Gartnerago theta, which constrains theage ofilie samples to between CC9a (FO ofE. turriseiffelii)
to CC I Oa (LO of G. theta). The marker-species for
subzones within CC9 and CCIO (Corollithion kennedyi,
Lithraphidites
acutus,He le ne achiastia,
Axopodorhabdus albianus) were not observed, and areassumed not to have been present on the Russian Craton

109===========================

Journal of Nannoplankton Research , 19. 2. 1997.

J. Hendericks & P Ziveri.· Orastrum colligatum, a new species ..... p. 109-111.

Platform. In the lower samples. Serib iscutum primilii'UIII(samples 94K4/6-10) and Gartnerago nanum are alsopresent. Mortimer ( 1987) defined zones in the Southern
Norwegian and Danish North Sea area based on the last
down hole occurrences (LOOs) of G. nanum (top ofNK 19)
and S. primitivum (top of NK 18). He appears to haveequated the LDO of the former to the first occurrence (FO)of L. acutus (that is. the base of CC I Oa). and the LOO ofS.
primitivum was shown to fall between the FO of L. acutus
and the last occurrences (LOs) of Rhagodiscus asper andA . albianus (that is, somewhere higher in CC I Oa) (seeMortimer, 1987. fig.8) . According to Burnett (in press),the range of G. theta is from the Lower CenomanianMantelliceras mantelli Ammonite Zone (CC9b) to theMiddle Cenomanian Acanthoceras rhotomagense
Ammonite Zone (CClOa). and it is therefore likely thatthe range of 0. co lligatum is CC9b-1 Oa (uppermost
Albian/lowermost Cenomanian to Middle Cenomanian).
Similar holococcoliths have been observed in Upper
Albian deposits of the North Sea in the area of the South
Halibut Basin (Dr. L. Gallagher, pers. comm. , 1997). The
LO of 0. colligatum was observed in samples 94K4/13(V)and 94K28/8(1) (Henderiks, 1996).
Holotype: Plate 1, Figure I: negative RGM-342 405; sample 94K4/10.
Parat~· pes: Plate 1. Figures 2-7; negatives RGM-342 400/402/406/408/409/41 O: sample 94K4/l 0.
Type locality: Section Kiev 94K4 , Bryansk region.
350km SW ofMoscow (see llyin. 1994. fig.3. section V).
T~' lle level: Section Kiev 94K4, 5.65 m below a facies
change from glauconitic sands into chalks. This facies
change is associated with the Cenomanian-Turonian
Boundary Event (Henderiks, 1996).

Acknowledgements
We wish to thank Jackie Burnett. Katharina von Salis
Perch-Nielsen, Ben Prins and Jan van Hinte who provided
helpful suggestions: Bruce Fouke and Alexandra
Nederbragt for initiating the project; and Saskia Kars for
supplying the SEM images taken at the Vrije Universiteit.
Amsterdam.
Rl'frt·cncrs
f3own , P.R. (E d .) In pre ss . C alcareous nann ofossil
bios/ratigraphy. Chapman & Hall , London.
Burnett, J.A In press. Upper Cretaceous. In : Bown . P.R . (Ed .)Calcareous nallllO.(ossil hiostratigraphy. Chapman & Hall ,London.
Parhan , A.J .. Hurnett , J .A., Bown , P.R. & Lord. A.R. 1994 .
l lolo<.:o<.:coliths from the Upper Cretaceous of Alabama andMiss issippi (U.S.A.). Cahiers de Micropaleontologie, 9(2):57-63.
Henderiks, J. 1996. Ccnomanian-Turonian Calcareous Nan noplankton of the Ru ssian Craton Platlorm: Biostratigraphy
and Palcoceanograph y. Unpublished report, Vrijc
Univcrsiteit. Amsterdam: I 02 pp ..
Ilyin , A. V. 1994. Cenoman ian phosp horites in the Former Soviet Union. S edimentary Geologv, 9-t: I 09- 1'27 .
Jakubowski, M. 1986. New calcareous nannofo ss il taxa fromthe Lower Cretaceous of the North Sea. INA News /et/er,
8(1 ): 38-42.
Mortimcr, C.P. 1987 . Upper C reta<.:eou s Nannofossil
Biostratigraphy of the Southern Norwegian and Danish
North Sea Area . Proceedings of the INA f·l·emw Afeeting.
1985 . .-1blumdhmgen der Geologisches Bundesanstalt, 39:
143-1 75.
Pcrch -Niclsen , K. 1985 . Mcsozoic calcareous nannofossils. /n :1-LM. l3olli , J.l3. Saundcrs & K. Per<.:h-Niclscn (Eds) . Plankton Stratigraphy: 329-426 . Cambridge University Press.
Sissingh . W. 1977. Biostratigraphy of Cretaceous calcareousnannoplankton . Geologie en Mijnhouw , 56( I): 37-65 .

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Journal of Nannopl ankton Research, 19, 2, 1997.

J. Hendericks & P Z1veri : Orastrum colligatum, a new species .... , p. 109-111.

PLATE 112

3

4
Figs 1-7 Orastrum colligatum nov. sp.
Henderiks & Ziveri

all scale bars 1 IJm

Holotype:56

1. Distal view, RGM -342 405. Upper Albian-Lower
Cenomanian (Sample 94K4/10 -Bryansk, Ukraine).

Paratypes:
2. Distal view, RGM -342 400. As 1.
3. Proximal view, RGM -342 406. As 1.
4. Proximal view, RGM -342 402. As 1.
5. Crossed-polars, RGM -342 409. As 1.

6. Phase-contrast, RGM -342 410. As 1.
7. Crossed-polars, RGM -342 408. Scale bar 10 IJm.
As 1.

7111